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Chapter 21
21.1.2 Reset at power-on
Note
Supply voltage
(V
)
DD
Internal reference
voltage (VPOC)
RESPOC
Reset period
Figure 21-2
708
The Power-On-Clear circuit (POC) permanently compares the power supply
voltage V
with an internal reference voltage (V
DD
microcontroller only operates as long as the power supply exceeds a well-
defined limit.
When the power supply voltage falls below the internal reference voltage
(V
< V
), the internal reset signal RESPOC is generated.
DD
IP
After Power-On-Clear reset, the RESF register is cleared and the internal reset
SYSRES is generated.
1.
Depending on the supply voltage drop rate it may be required to apply an
external RESET signal additionally in order to avoid microcontroller
operation out of the specified operating conditions. For detailed electrical
characteristics refer to the Electrical Target Specification.
2.
POC shares the reference voltage supply with the power regulators.
Figure 21-2 on page 708 shows the generation of RESPOC by the Power-On-
Clear circuit.
The Power-On-Clear function holds the microcontroller in reset state as long
as the power supply voltage does not exceed the threshold level VPOC.
Delay
Reset generation by Power-On-Clear circuit
User's Manual U18743EE1V2UM00
Reset period
). It ensures that the
IP
Time
Reset period
Reset
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